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2011
Neagu, E. R., C. J. Dias, M. C. Lanca, R. Igreja, P. Inacio, J. N. Marat-Mendes, and Ieee Discrimination between Space Charge and Dipolar Contributions in Ferroelectric Polymers., 2011. AbstractWebsite

The final thermally stimulated discharge current method allows a better selection of the experimental conditions for sample polarization. By decreasing the ratio between the charging time and the discharging time, the apparent peak is of the same order of magnitude as the genuine peaks and there is only a partial overlap between then. Two peaks have been identified for polyamide 11, one associated with the glass transition around 60 degrees C and the second associated with the Curie transition around 96 degrees C.

Neagu, E. R., C. J. Dias, M. C. Lanca, R. Igreja, P. Inacio, J. N. Marat-Mendes, and Ieee. "Discrimination between Space Charge and Dipolar Contributions in Ferroelectric Polymers." 2011 14th International Symposium on Electrets (Ise) (2011): 145-146. Abstract
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Fidalgo, Patr{\'ıcia, and João Correia de Freitas. "Does size matters? A pilot study on network types created in a Learning Management System." World Conference on Educational Multimedia, Hypermedia and Telecommunications. Vol. 2011. Editilib, 2011. 729-734. Abstract
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Fidalgo, Patr{\'ıcia, and João Correia de Freitas. "Does Teacher’s Experience Matters? Social Network Analysis Applied to Learning Forums." VII Conferência Internacional de TIC na Educação - Challenges 2011 - Perspectivas de Inovação. Centro de Competência da Universidade do Minho ISBN 978-972-98456-9-7, 2011. 1389-1402. Abstract
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O'Brien, S.a, Çopuroglu Tassie Nolan Hamilton Povey Pereira Martins Fortunato Pemble M. a P. b. "The effect of dopants on the morphology, microstructure and electrical properties of transparent zinc oxide films prepared by the sol-gel method." Thin Solid Films. 520 (2011): 1174-1177. AbstractWebsite

The influence of doping on the morphology, physical and electrical properties of zinc oxide produced by the sol-gel method was examined. Undoped zinc oxide was observed to form relatively porous films. Addition of an Al dopant influenced the sheet resistance, but did not result in a change in morphology, examined by atomic force microscopy when compared to undoped films. In the case of electrical measurements, undoped ZnO films were extremely resistive. A minimum dopant concentration of 2 at.%. Al was required to produce materials which were more conductive, as observed by sheet resistance measurements, which were shown to vary with annealing temperature. The versatile nature of sol-gel processing was demonstrated by selective ink-jet deposition of sol-gel droplets which were annealed to form oxide materials. © 2011 Elsevier B.V. All rights reserved.

Parthiban, S.a b, Elangovan Ramamurthi Kanjilal Asokan Martins Fortunato E. b K. a. "Effect of Li3+ heavy ion irradiation on the Mo doped In2O3 thin films prepared by spray pyrolysis technique." Journal of Physics D: Applied Physics. 44 (2011). AbstractWebsite

The high visible-near infrared transparent and high carrier mobility (μ) Mo doped (0.5 at%) indium oxide (IMO) films were deposited by the spray pyrolysis technique. The deposited films were irradiated by 50MeV Li 3+ ions with different fluences of 1×1011, 1×1012 and 1×1013 ions cm-2. X-ray diffraction analysis confirmed the cubic bixbyite structure of indium oxide. A fascinating feature is that the ion irradiation process has introduced a fraction of the molybdenum oxide phase. The μ of as-deposited IMO films is decreased from ̃122.4 to 93.3 cm2 V-1 s-1, following the ion irradiation. The theoretically calculated μ and carrier density values were correlated with those measured experimentally. The transport mechanism has been analysed based on the ionized and neutral impurity scattering centres. The average transmittance (400-2500 nm) of the as-deposited IMO films is decreased from 83% to 60% following irradiation. © 2011 IOP Publishing Ltd.

Mendonça, E., M. Diniz, L. Silva, I. Peres, L. Castro, J. B. Correia, and A. Picado. "Effects of diamond nanoparticle exposure on the internal structure and reproduction of Daphnia magna." Journal of Hazardous Materials. 186 (2011): 265-271. AbstractWebsite
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c Gokulakrishnan, V.a, Parthiban Elangovan Ramamurthi Jeganathan Kanjilal Asokan Martins Fortunato S. a E. c. "Effects of O7+ swift heavy ion irradiation on indium oxide thin films." Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms. 269 (2011): 1836-1840. AbstractWebsite

Indium oxide thin films deposited by spray pyrolysis were irradiated by 100 MeV O7+ ions with different fluences of 5 × 1011, 1 × 1012 and 1 × 1013 ions/cm2. X-ray diffraction analysis confirmed the structure of indium oxide with cubic bixbyite. The strongest (2 2 2) orientation observed from the as-deposited films was shifted to (4 0 0) after irradiation. Furthermore, the intensity of the (4 0 0) orientation was decreased with increasing fluence together with an increase in (2 2 2) intensity. Films irradiated with maximum fluence exhibited an amorphous component. The mobility of the as-deposited indium oxide films was decreased from ∼78.9 to 43.0 cm2/V s, following irradiation. Films irradiated with a fluence of 5 × 1011 ions/cm2 showed a better combination of electrical properties, with a resistivity of 4.57 × 10-3 Ω cm, carrier concentration of 2.2 × 1019 cm-3 and mobility of 61.0 cm2/V s. The average transmittance obtained from the as-deposited films decreased from ∼81% to 72%, when irradiated with a fluence of 5 × 1011 ions/cm2. The surface microstructures confirmed that the irregularly shaped grains seen on the surface of the as-deposited films is modified as "radish-like" morphology when irradiated with a fluence of 5 × 1011 ions/cm2. © 2011 Elsevier B.V. All rights reserved.

Valtchev, Stanimir. "The Efficient and Stable Charging of Electric Vehicle Batteries: Simplified Instantaneous Regulation." International Symposium on Electric Vehicles ISEV2011, presentation 03084, Beijing. 2011. Abstract
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M.C., LANÇA, NEAGU E.R., DIAS C.J., GIL L., and MARAT-MENDES J.N. "Electrical properties of cork and derivatives." 23.3/4 (2011). Abstract
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Cordas, C. M., J. Wilton, T. Cardoso, F. Folgosa, AS Pereira, and P. Tavares. "Electrochemical behaviour of Dps-a mini-ferritin." European Biophysics Journal with Biophysics Letters. 40 (2011): 181. AbstractWebsite
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Valtchev, Stanimir. "Electromagnetic Field as Wireless Transporter of Energy." 10th International Conference on Applied Electromagnetics (\cyrchar\CYRP\cyrchar\CYRE\cyrchar\CYRS Conference). 2011. Abstract
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Martins, R., I. Ferreira, and E. Fortunato. "Electronics with and on paper." physica status solidi (RRL)-Rapid Research Letters. 5.9 (2011): 332-335. Abstract
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Martins, R., Ferreira Fortunato I. E. "Electronics with and on paper." Physica Status Solidi - Rapid Research Letters. 5 (2011): 332-335. AbstractWebsite

Today there is a strong interest in the scientific and industrial community concerning the use of biopolymers for electronic applications, driven mainly by low-cost and disposable applications. Adding to this interest, we must recognise the importance of the dream of wireless auto-sustained and low-energy-consumption electronics. This dream can be fulfilled by cellulose paper, the lightest and the cheapest known substrate material, as well as the Earth's major biopolymer and of tremendous global economic importance. Most of the paper used up to now is optimised in terms of the required mechanical and physical properties to be used as the support of inks of different origins. In the future, specific electronic heterogeneous paper sheets should be fabricated aiming to get paper fibers with required bulk and surface functionalities, proper water/vapour barrier, size and diameter/thickness of the fibrils and full paper thickness. This will be the function of components/devices to be incorporated/integrated such as thin-film transistors, complementary metal oxide semiconductor devices, passive electronic components (resistances, inductors and capacitors), memory transistors, electrochromics and thin-film paper batteries. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Araújo, João, and Michael Kinyon. "An elegant 3-basis for inverse semigroups." Semigroup Forum. 82 (2011): 319-323. AbstractWebsite
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Valtchev, Stanimir. "Energy Harvesting and the Human Health." First Conference with International Participation {"}Education, Science, Innovations{"} Proceedings of ESIʹ2011, pp. 451-460. 2011. Abstract
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Valtchev, Stanimir. "The Energy That’s Around." {Conference “Millennium Development Goals”. 2011. Abstract
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Nayak, P.K., Pinto Gonçalves Martins Fortunato J. V. G. "Environmental, optical, and electrical stability study of solution-processed zinc-tin-oxide thin-film transistors." IEEE/OSA Journal of Display Technology. 7 (2011): 640-643. AbstractWebsite

In this paper, we report the environmental, optical, and gate bias stress stability of amorphous zinc-tin-oxide (ZTO) thin-film transistors (TFTs) fabricated by sol-gel spin-coating method. The ZTO TFTs showed excellent environmental and optical stability. The threshold voltage stability of ZTO TFTs was sensitive to both positive and negative gate bias stress. Maximum threshold voltage shifting of +1.9 and -3.2 V was observed under a gate bias stress of +10 and -10 V, respectively, with no significant change to subthreshold swing value. © 2006 IEEE.

Diniz, M. S., R. Pereira, A. C. Freitas, T. A. P. Rocha-Santos, L. Castro, I. Peres, and A. C. Duarte. "Evaluation of the sub-lethal toxicity of bleached kraft pulp mill effluent to carassius auratus and dicentrarchus labrax." Water, Air, and Soil Pollution. 217 (2011): 35-45. AbstractWebsite
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Marques, Filipe J., and Carlos A. Coelho. "The exact and near-exact distributions of the likelihood ratio test statistics for testing circular symmetry." Univ. Nova de Lisboa, CMA. 1 (2011): 2011. Abstract
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Inácio, David, João Pina, Go{\cn}alo Luis, João F. Martins, Mário Neves, and Alfredo Alvarez. "Experimental Characterization of a Conventional (Aluminum) and of a Superconducting (YBCO) Axial Flux Disc Motor." IEEE Transactions on Applied Superconductivity. 21 (2011): 1146-1150. AbstractWebsite

An equivalent model and electromechanical characteristics for the disk motor was obtained based on the Steinmetz parameters. This paper describes a series of tests conducted on an axial flux motor, equipped with an aluminum rotor disc and an YBCO high temperature superconducting rotor disc, at liquid nitrogen temperature (77 K). The rotating magnetic field was produced by a four-pole, three-phase stator winding, at 50 Hz. At asynchronous permanent regime, Steinmetz-type models are able to describe both motors' behavior. From the performed tests, the parameters of both motors' models were deduced. A variable load was used to obtain both motor's characteristics (conventional and superconducting). Experimental obtained characteristics of both motors are compared with the ones predicted from parameters' calculation. The HTS motor provides high efficiency then the conventional ones.

Igreja, Rui, and C. J. Dias. "Extension to the analytical model of the interdigital electrodes capacitance for a multi-layered structure." Sensors and Actuators a-Physical. 172 (2011): 392-399. Abstract

Interdigital electrodes (IE) are one of the most used transducers in different technical and analytical applications with the particular importance in the field of chemical and biological sensors. With the recent demand for lab-on-a-chip devices and the need for sensors miniaturization it becomes common the use of such transducers in structures with several dielectric layers (either substrates or superstrates). In a previous a work we proposed a model for the computation of the capacitance of these multi-layered structures using the techniques of conformal mapping and partial capacitance. Until now, that model has been used in applications where the permittivity of consecutive layers monotonically decreases from layer to layer (as we move away from the electrodes plane) giving excellent results. New applications, such as the use of Si/SiO2 substrates (to promote very smooth surfaces for electrodes deposition) or the use of passivation layers for the protection of electrodes (e.g. from liquids), among others, represent a new challenge for the computation of the overall capacitance since in these devices the permittivity can decrease from layer to layer. Under these conditions the original partial capacitance technique needs to be modified to include these new configurations. In this work we will discuss a new approach, splitting the concept of partial capacitance in parallel partial capacitance and serial partial capacitance where new conformal mapping transformations are proposed for the latter case. Hence this novel approach will extend our previous analytical model in order to account for the cases where there is a decrease in the permittivity from layer to layer. The results are compared with finite element simulation and experimental results. (C) 2011 Elsevier B.V. All rights reserved.

Igreja, R., and C. J. Dias. "Extension to the analytical model of the interdigital electrodes capacitance for a multi-layered structure." Sensors and Actuators a-Physical. 172 (2011): 392-399. AbstractWebsite
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Sebastião, PJ, A. Gradisek, LFV Pinto, T. Apih, M. H. Godinho, and M. Vilfan. "Fast field-cycling NMR relaxometry study of chiral and nonchiral nematic liquid crystals." The Journal of Physical Chemistry B. 115.49 (2011): 14348-14358. Abstract
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